Endodontics is a specific branch of dentistry related to pathological treatment of dental pulp or apical tissue.
The inner part of a tooth contains nerves and blood vessel tissues called dental pulp, which is covered by dentin, and the outermost part of the tooth contains enamel. Endodontic treatment is conducted mainly when the dental pulp is infected.
Endodontic treatment of a tooth having pulp tissue in which inflammation is in progress or necrosis has occurred is generally conducted by opening an inner space of the tooth called a pulp chamber through an access cavity formed in a crown of the tooth, and putting an endodontic instrument into a canal within a root of the tooth.
After the endodontic treatment is finished, the root canal is sealed using a root canal filler to prevent secondary infection. An ideal dental root canal filler may be excellent in properties such as biocompatibility, bactericidal properties, sealing properties, stability, workability, injectability and dispersibility, and radiopacity.
Examples of the root canal filler may include gutta percha and a sealer. Endodontic treatment employing gutta percha and a sealer may be considered as conservative treatment. This is commonly conducted by two techniques, i.e., lateral and vertical condensation techniques. In the lateral condensation technique, a gutta percha cone is put inside a root canal and laterally condensed using a spreader tool to fill the root canal, and then empty space between the filled gutta percha and the root canal is filled with a sealer. In the vertical condensation technique, gutta percha is inserted in a root canal and vertically condensed using a plugger tool to fill the root canal.
However, according to those conventional techniques, there is a risk that the root canal could be fractured or damaged in the process of applying pressure to the gutta percha. Further, a tooth has a root canal system having complicated and diverse shapes, thus requiring more secure sealing.
Meanwhile, when a general endodontic treatment process is unsuccessfully conducted or a non-surgical treatment cannot fully remove inflamed tissues due to the state or condition of the tooth, a surgical endodontic treatment is conducted to preserve the tooth. In this case, what is most frequently conducted is to cut off a root apex of the tooth (i.e., to conduct apicoectomy) and prepare a cavity for retrograde filling at the tip thereof so that an artificial material is filled. According to the above, tissues or germs existing within the infected root canal cannot be disseminated to tissues around the tooth root (i.e., tissues around the root apex) so that inflammation of the tissues around the root apex may be prevented and the tooth may be preserved for a long period.
Various materials have been employed for retrograde filling of a root apex, and biological/physical assessments thereof are being diversely conducted. The known materials that may be considered include gutta percha, polycarboxylate cement, amalgam, Super-EBA, Cavit, zinc oxide, eugenol, glass-ionomer cement, zinc phosphate cement, and the like. However, it has been reported that some of the above materials have low biocompatibility or have poor physical properties making them unsuitable for use in a surgical environment where blood or other moisture exists.
In contrast, MTA (mineral trioxide aggregate) cement is known as a material having excellent biocompatibility and sealing properties. It has become a typical dental material that may be extensively used for retrograde filling of a root apex and closing of perforation, and may be employed in procedures including pulp capping, pulpotomy, artificial apical barrier placement (apexification), revascularization and apexogenesis procedure, and the like. Therefore, since the MTA cement is hardened with water and thus has good sealing properties in a humid environment, diverse efforts are being made to employ it for root canal filling, and among those, researches on using the MTA cement made in the form of paste are being actively conducted. In this connection, one example thereof may be the technique disclosed in Korean Laid-open Patent Publication No. 10-2010-0037979.
However, although it is generally assumed that a root canal is under a humid environment, every root canal is not always in a humid state since many dentists are familiar with drying the root canal in an endodontic treatment process. Further, the existing MTA cement products have low usability since they should be mixed with liquid immediately before being injected into the root canal, and have relatively poor flowability and manipulability so that it takes a long time for them to be positioned deep inside the root canal.
Therefore, the inventor(s) present a single paste type MTA cement that absorbs ambient moisture even in a dried root canal to securely harden within an appropriate time.